Iran has threatened to close the Straits of Hormuz – a “choke point” in the Persian Gulf through which about 20 percent of the world’s oil passes – if the West imposes sanctions against Iran’s petroleum exports. This threat is not without historic parallel. In 1941, Japan bombed Pearl Harbor and launched its war against the United States after Washington blockaded oil shipments to Tokyo. Japan relied on 80 percent of its oil from the United States; oil sales make up 80 percent of Iran’s exports. A complete oil embargo on Iran, just as it would have done to Imperial Japan, would result in economic calamity.